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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to manhole cover supports and, in particular, to a
separate ring placed within an existing manhole frame to raise the height
of the manhole cover to compensate for added roadway pavement. More
particularly, the invention relates to an improved method for installing
the ring in the manhole frame.
2. Description of the Prior Art
Most underground facilities such as sanitary and storm sewers, utility
conduits and the like have manhole openings to provide access thereto.
These manholes usually are located in the street or roadway and consist of
an inverted bell-shaped metal frame mounted on top of a brick or concrete
base structure. This metal frame has an internal ledge for supporting the
manhole cover so that the top of the cover is level with the top of the
frame and surrounding roadway pavement.
Problems arise quite frequently in the resurfacing of roadways in that a
layer of pavement is placed on the existing pavement, resulting in the
manhole cover being below the top surface of the new pavement causing a
depression in the roadway. It is quite difficult and expensive to raise
the existing manhole frame sufficiently to compensate for the added
pavement.
Various devices and methods have been constructed and used which enable an
existing manhole cover to be raised to the level of the new pavement
surface without raising the existing manhole frame. Examples of these
devices and methods are shown in U.S. Pat. Nos. 1,517,871, 3,218,943,
3,773,428, and 3,891,337.
Some of these prior art devices, although apparently providing the desired
results, are expensive to manufacture due to the number of machining and
forming operations required for their fabrication. Likewise, these devices
achieve their adjustment and/or clamping engagement with the manhole frame
by a threaded screw mechanism or inclined, frictionally retained wedge
which in time may become loose due to the continuous vibration caused by
passing vehicles. These screw mechanisms and wedges become corroded,
preventing removal of the elevating ring should their removal be required
in the future. Also, most known devices use an expanding mechanism which
protrudes into the I.D. of the manhole, thereby reducing the actual I.D.
as well as creating a work and safety hazard for workmen climbing into and
out of the manhole opening.
Many of the problems encountered with these known constructions and devices
are believed to be overcome by the manhole cover support ring shown in my
earlier U.S. Pat. No. 4,097,171. Use of the manhole cover elevating and
support ring of U.S. Pat. No. 4,097,171 in actual field installations
indicates that the construction is performing quite satisfactorily.
However, it is important for nearly all manufacturers to be able to provide
their products at as low a cost as possible without sacrificing quality.
The present invention provides an elevating ring construction and a method
of installing the same in a manhole frame which reduces the cost of my
previously patented support ring while providing the same satisfactory
results. This reduction in cost is achieved by eliminating the toggle
mechanism and the mounting of this mechanism on the elevating ring so it
functions as an integral part of the ring construction. Cost reduction
also is achieved during installation by eliminating some of the operations
which may be required to be performed on the ring in the field by the
workmen.
No known manhole cover elevating and support ring and method of installing
the same of which I am aware uses the natural elasticity in a compressed
split metal ring to clamp the ring within the manhole cover frame, or uses
a separate adjustable link that is force-fitted within a gap formed in the
split ring, alone or in combination with the elasticity of the compressed
ring, to clamp the ring in the frame opening.
SUMMARY OF THE INVENTION
Objectives of the invention include providing an apparatus for adjusting
the elevation of manhole covers within a manhole frame opening by
providing a ring formed relatively inexpensively of a flat strip of metal
rolled circular and a strip of rectangular bar stock rolled circular which
are welded together with a predetermined sized gap existing between the
adjacent spaced ends of the ring, and in which the metal ring possesses
sufficient natural elasticity that after being partially compressed and
placed within a manhole frame opening will expand outwardly against the
sides of an existing manhole frame opening with sufficient force to become
firmly seated therein, or in which an extremely inexpensive and simple
adjustable link is force-fitted between the spaced ends of the ring by a
hammer or similar tool to install the ring in the frame opening; providing
such an apparatus in which the ring can be removed from the frame opening
by loosening the force-fit engagement of the link with the spaced ring
ends by shortening the length of the link by a simple rotation of one of
the link components by use of a pliers or similar tool; providing such an
apparatus in which a keeper formed by an inexpensive strip of spring metal
is placed between the spaced ends of the ring in a bowed engagement with
the installed link to further insure retention of the link in engagement
with the spaced ends of the ring; providing such a mechanism in which the
link is easily adjusted to regulate the limits of outward expansion of the
ring so as to compensate for and accommodate various sizes of openings in
manhole covers and irregularities of roundness in both the frame opening
and elevating ring; providing such an apparatus in which the adjustable
link provides a high mechanical advantage and a positive force-fit
engagement with the elevating ring which adjusts the ring to minor manhole
variations in the field and which cannot be readily loosened by
vehicle-caused vibrations which is a problem with a frictionally held
wedge-fit engagement; providing such an apparatus in which the link lies
within the periphery of the elevating ring without any components
protruding into the I.D. of the manhole frame opening, thereby eliminating
a work hazard; and providing such an apparatus for elevating a manhole
cover which is relatively inexpensive, which eliminates difficulties
heretofore encountered with prior devices, achieves the stated objectives
simply, effectively and efficiently, and solves problems and satisfies
existing needs.
Further objectives of the invention include providing an improved method of
adjusting the elevation of a manhole cover by initially roll forming an
inexpensive elevating ring from metal stock into an annular configuration
having a predetermined size gap between the spaced ends of the rolled
strip, preferably at a location remote from the installation site;
providing such an improved method in which the roll formed ring is
radially compressed and retained in this compressed condition by
restraining means such as an encircling banding strap or the like and is
subsequently shipped to the job site and dropped into the manhole frame
opening, whereupon the retaining band or other restraining means is
removed and the ring expands outwardly into clamping engagement with the
frame opening; providing such an improved method in which a manually
adjustable link may be force-fitted within the gap of the split ring after
its installation in a manhole frame opening to assist in forcibly
expanding the ring outwardly into engagement with the frame opening, and
in which a spring biased metal keeper strip also may be installed within
the gap of the split ring to increase the reliability thereof by locking
the link in the ring gap; and providing such an improved method which
reduces the amount of work required to be performed at the job site, and
which provides an extremely simple, inexpensive and effective method of
adjusting the height of a manhole cover.
These objectives and advantages are obtained by the improved apparatus for
adjusting the elevation of a manhole cover within a manhole frame, the
general nature of which may be stated as including circular ring means
having inwardly projecting manhole cover supporting ledge means and
upstanding flange means, said ring means being split at least at one point
on its periphery forming a gap between a pair of spaced end portions;
adjustable link means adapted to be forcibly placed within the gap and
extend between the spaced end portions of the ring means to expand the
ring means outwardly forcing the flange means into abutting engagement
with the manhole frame; the link means including a sleeve having inner and
outer ends with an internally threaded axially extending opening
communicating with the inner end, and a bolt threadedly engaged in said
opening and extending axially therefrom; and the outer end of the sleeve
and the bolt each engaging a respective spaced end of the ring means.
These objectives and advantages are further obtained by the improved method
of adjusting the elevation of a manhole cover, the nature of which may be
stated as including the steps of forming an annular elevating ring split
at one point on its periphery to form a predetermined size gap between a
pair of spaced end portions; radially compressing the split ring to move
the end portions closer to each other; restraining the elevating ring in
the compressed position; placing the restrained, compressed elevating ring
within the circular opening of a manhole frame; removing the restraint on
the elevating ring permitting the ring to expand outwardly toward its
originally formed condition forcing the ring into abutting engagement with
the manhole frame; installing an adjustable link in the gap between the
spaced end portions with a force-fit to assist the outward expansion of
the elevating ring; and installing a spring biased keeper between and
operatively engageable with the spaced end portions to assist in
maintaining the link in engagement with the spaced end portions.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the invention--illustrative of the best mode in
which applicant has contemplated applying the principles--is set forth in
the following description and shown in the accompanying drawings, and is
particularly and distinctly pointed out and set forth in the appended
claims.
FIG. 1 is a top plan view of the elevating ring in its rolled, normal
expanded condition;
FIG. 2 is an enlarged front elevational view looking in the direction of
arrows 2--2, FIG. 1;
FIG. 3 is an enlarged sectional view taken on line 3--3, FIG. 1;
FIG. 4 is a view similar to FIG. 2 showing the elevating ring in a
compressed, restrained position;
FIG. 5 is a greatly enlarged fragmentary top plan view showing a modified
means of restraining the elevating ring in a compressed condition;
FIG. 6 is a top plan view showing the compressed, restrained elevating ring
of FIG. 4 placed within a circular manhole frame opening;
FIG. 7 is a fragmentary top plan view showing the elevating ring in an
expanded clamping position within the manhole frame opening with the
adjustable link installed in the ring gap;
FIG. 8 is an enlarged fragmentary elevational view looking in the direction
of arrows 8--8, FIG. 7, of the adjustable link when initially placed
within the ring gap prior to moving the link to its installed locked
position;
FIG. 9 is a fragmentary elevational view similar to FIG. 8 showing the
adjustable link in installed position, with a spring biased keeper mounted
in the ring gap to assist in retaining the link therein;
FIG. 10 is an enlarged sectional view taken on line 10--10, FIG. 8;
FIG. 11 is an enlarged fragmentary elevational view looking in the
direction of arrows 11--11, FIG. 8; and
FIG. 12 is a diagrammatic sectional view of the improved manhole cover
elevating apparatus supporting a manhole cover on an existing manhole
frame.
Similar numerals refer to similar parts throughout the drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The improved apparatus for adjusting the elevation of a manhole cover is
shown in the drawings and includes as a main component a manhole cover
support and elevating ring, indicated generally at 1 (FIGS. 1, 2 and 3).
Ring 1 includes a generally vertical flange 2 and a lower manhole cover
support bar 3. Flange 2 is formed of a relatively flat metal strip with
bar 3 being formed from bar stock, preferably having a rectangular
cross-sectional configuration as shown in FIG. 3. Bar 3 is attached by
welds 4 to the bottom portion of flange 2. Flange 2 and bar 3 are welded
in a flat condition and then are formed into the circular configuration of
FIG. 1. Bar 3 lies radially inwardly or inside of the periphery of flange
2 for supporting a manhole cover thereon.
Flange 2 and bar 3, when rolled into the circular configuration of ring 1,
form a predetermined size gap 6 extending between a pair of spaced ring
ends 7 and 8. In an example of ring 1 for a usual installation, bar 3 will
be hot-rolled, low-carbon 1020 AISI steel, approximately 3/4 of an inch
thick and 2 inches high. Flange 2 will be formed of twelve gauge similar
type steel and will extend upwardly beyond the top of bar 3 approximately
1 to 3 inches, the amount of which depends upon the particular thickness
of the manhole covers to be inserted therein. For the example given above,
ring 1 will have a diameter of approximately 24 inches, with gap 6 being
approximately 41/2 inches.
Manhole frames used by most cities and municipalities have predetermined
size openings so that the required diameter of ring 1 is known at time of
construction. In the event the particular manhole opening in which ring 1
will be used varies from a standard size, the diameter of the ring can be
changed by varying the length of flange 2 and bar 3 prior to roll forming
them into their circular configuration. Flange 2 when welded on bar 3 will
extend slightly outwardly from a true vertical position at an angle of
approximately 3.degree., as shown in FIG. 3, to form a frustro conical
configuration in order to be complementary with the tapered sides provided
on most manhole covers.
In accordance with one of the features of the invention, an adjustable
link, indicated generally at 10 (FIGS. 7, 8 and 9), is used to expand ring
1 within the opening of a manhole frame, as shown in FIG. 12. Link 10 is
formed by a tubular sleeve 13 having an internally threaded, axially
extending central bore 14 which extends partially into sleeve 13 from
inner sleeve end 15. Outer sleeve end 16 is formed with a chisel-like
point 17. A threaded bolt 18 is adjustably engaged within bore 14 and has
an outer rounded end 19.
FIG. 12 shows elevating ring 1 mounted in a manhole opening 21. A usual
manhole consists of a bell-shaped frame 22 which is mounted on the top of
a brick water catch basin 20. Frame 22 has an annular, horizontal manhole
cover supporting ledge 23 which terminates in an upwardly, generally
outwardly extending, conical wall 26. Wall 26 is connected with outer bell
surface 24 by an annular horizontal top surface 25. The top surface 27 of
the original road pavement 28 is generally level with top surface 25 of
frame 22 and with top surface 29 of a manhole cover 30 when cover 30 is
supported on horizontal ledge 23.
When installing ring 1, all dirt, rust and debris is removed from ledge 23
and conical wall 26 of manhole frame 22. Ring 1 then is placed within
manhole opening 21, which is defined by frame wall 26, with adjustable
link 10 being placed in gap 6, as shown in FIGS. 8, 9 and 10. Bolt end 19
is placed within a concave recess 33 formed in ring end portion 8 (FIG.
11). Link 10 then is moved from the position of FIG. 8 to that of FIG. 9
by several blows, such as by hammer, which are delivered in the direction
of arrow A (FIG. 8). These blows pivot link 10 downwardly in a
counterclockwise direction to the installed position of FIG. 9 expanding
ring 1 outwardly and clamping it tightly against conical surface 26.
Chisel point 17, if sufficient force is applied to link 10, will cut into
the metal of end wall portion 7 until reaching the installed position of
FIG. 9, thereby locking it securely in this position. Considerable force
can be applied by a hammer or the like to link 10, which force is
distributed throughout ring 1, forcing it into a very tight clamping
engagement with frame wall 26. Link 10 is manually adjusted prior to
forcing it to its lower position by relative rotation between sleeve 13
and bolt 18. This adjustment enables ring 1 to be used for various manhole
openings and to be able to compensate for minor ring variations
encountered at the job site. This is especially important since ring 1 and
manhole frame 22 are not machined parts and therefore will vary somewhat
in dimensions.
Link 10 enables a very high mechanical advantage to be achieved which is
not possible with many known elevating ring constructions. Also, no manual
adjustment of bolts or other threaded expanders is required after the
expanding member is under stress in order to achieve the clamping
engagement as in prior constructions, since link 10 is adjusted prior to
locking the same in gap 6.
Another secondary feature of the invention is the use of a keeper 34 (FIG.
9) to completely insure the retention of link 10 in its installed position
to increase the reliability of the improved manhole cover elevating
apparatus. Keeper 34 is a short flat strip of spring metal which can be
cut in the field and inserted in gap 6, as shown in FIG. 9, with its ends
engaging end wall portions 7 and 8. Keeper 34 is pressed downwardly (arrow
B, FIG. 10) against link 10 forming a concavely bowed, biased
configuration. Once keeper 34 is installed in this bowed position,
considerable force would be required to move keeper 34 upwardly and out of
engagement with link 10. Keeper 34 reduces the possibility of vehicle
vibrations slowly but continuously moving link 10 upwardly since these
vibrational forces are too low to overcome the bias of keeper 34.
After link 10 is driven from the position of FIG. 8 to that of FIG. 9 and
keeper 34 installed, cover 30 is placed on top surface 44 of bar 3 in a
usual manner with its top surface 29 being generally level with the top
surface of new pavement layer 35. If desired, a gasket (not shown) may be
placed between manhole 30 and bar surface 44 to reduce metal-to-metal
contact noise when driven over by a vehicle.
In further accordance with the invention, the improved method of installing
elevating ring 1 is shown generally in FIGS. 1-6. The initial step of this
method includes the roll-forming of welded bar members 2 and 3 into the
circular, split ring configuration of FIG. 1. Ring 1 will have a
predetermined diameter and gap 6, depending upon the particular size of
the manhole opening in which it is to be installed. The O.D. of ring 1,
however, will be larger than the inside diameter of manhole opening 21
defined by frame wall 26.
The next step of the improved method consists of compressing ring 1 by some
means to partially close gap 6. After ring 1 is compressed, a band 37 or
other restraining means, maintains ring 1 in the compressed state. This is
particularly illustrated in FIGS. 2 and 4 wherein ring 1 is shown in FIG.
2 in its rolled, normal position with gap 6 having a predetermined size,
which is considerably reduced when compressed, as shown in FIG. 4. Band 37
may be a usual steel strap connected by a clamp 38.
FIG. 5 shows another means of retaining ring 1 in a compressed state. A
short section of rigid wire 40, one end of which is formed with an offset
41, is inserted through an opening 42 formed in flange 2. Opposite angled
end 43 is inserted through an opposite side opening 44, whereafter wire
end 43 is bent downwardly against ring 1 from the dot-dash line position
to the full line position of FIG. 5, retaining ring 1 in its compressed
condition.
The above operations preferably are performed at a location generally
remote from the job site, preferably at the manufacturer's premises. These
restrained, compressed elevating rings then are shipped to a job site for
installation.
FIG. 6 shows generally diagrammatically the next step of the improved
method. Compressed ring 1, the O.D. of which has been reduced to an amount
less than the I.D. of manhole opening 21, is placed within opening 21 upon
horizontal frame ledge 23. Band 37 or wire 40 then is cut by a usual tool,
whereupon the natural elasticity in the compressed ring metal will expand
the ring outwardly attempting to return it to its natural "at rest"
configuration of FIG. 1. This elasticity will tightly clamp the ring
against frame surface 26. Thus, at a job site, the workmen only need to
lower ring 1 onto cover support ledge 23 of a manhole frame and then break
or cut band 37, whereupon ring 1 automatically clamps itself in position.
For a typical installation, ring 1 may have a diameter of 24 inches with
gap 6 being approximately 41/2 inches. This gap distance is compressed to
approximately 2 inches (FIG. 4) and is so designed so that after release
of the restraining means it will expand to a gap of approximately 21/2
inches. Thus, it is easily understood that a considerable outward
expansion force is continuously exerted by the ring against the manhole
frame in attempting to return to its natural, prestressed position.
For many installations, no additional components or equipment will be
required in that the expansion force exerted by the ring itself will be
sufficient to retain ring 1 in installed position, whereupon manhole cover
30 is placed upon and supported by top surface 44 of ring bar 3.
It may be preferable for certain installations that a secondary locking
means be used with expanded ring 1 to insure its mounting within the
manhole frame. Link 10, the construction and use of which is described
above, preferably is inserted in gap 6 to completely lock ring 1 in
clamping position. Keeper 34 then may be installed in gap 6 to completely
insure link 10 remaining in position.
Accordingly, the improved manhole cover elevating apparatus and method of
installing the same provides a construction which is formed of a few
relatively inexpensive and readily available components which are
assembled by usual hand tools; provides a construction in which the
compressed ring may have sufficient force to maintain itself in an
installed position without requiring any additional retaining or locking
components, and even if used with additional locking components, the
resulting structure will not reduce the effective I.D. of the manhole
opening nor require time-consuming expanding procedures, such as expanding
the ring by tightening bolts or similar operations used by prior
constructions; and provides a construction and method which is simplified,
effective and safe in operation, which eliminates difficulties existing in
the art, and which achieves the stated objectives and solves problems
which have existed in the art.
In the foregoing description, certain terms have been used for brevity,
clearness and understanding but no unnecessary limitations are to be
implied therefrom beyond the requirements of the prior art, because such
terms are used for descriptive purposes and are intended to be broadly
construed.
Moreover, the description and illustration of the invention is by way of
example, and the scope of the invention is not limited to the exact
details of the construction shown or described.
Having now described the features, discoveries and principles of the
invention, the manner in which the improved method and apparatus for
adjusting the elevation of manhole covers is assembled and operated, the
characteristics of the new method and construction, and the advantageous,
new and useful results obtained; the new and useful structures, devices,
elements, arrangements, parts, method steps, and combinations thereof are
set forth in the appended claims.
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